c-- ccc ccd cco ccp ccs cdc cdd cdo cdp cds co- coc cod coo cop cos cpc cpd cpo cpp cps csc csd cso csp css dcc dcd dco dcp dcs ddc ddd ddo ddp dds doc dod doo dop dos dpc dpd dpo dpp dps dsc dsd dso dsp dss oc- occ ocd oco ocp ocs odc odd odo odp ods oo- ooc ood ooo oop oos op- opc opd opo opp ops os- osc osd oso osp oss p-p pcc pcd pco pcp pcs pdc pdd pdo pdp pds poc pod poo pop pos ppc ppd ppo ppp pps ps- psc psd pso psp pss scc scd sco scp scs sdc sdd sdo sdp sds soc sod soo sop sos spc spd spo spp sps ss- ssc ssd sso ssp sss